**Recent Met Office guidance points to a minimum of 14°C for London on 5 August, yet trader sentiment clusters tightly around 18–19°C because models still show meaningful uncertainty in overnight radiative cooling two days out.** Persistent above-average nighttime temperatures this summer—driven by warm advection and limited clear-sky periods—have kept recent lows elevated, with the UK mean minimum running roughly 1.5 °C above the 1991–2020 climatology through early August. Key variables separating the leading 18 °C and 19 °C bins include the precise arrival time of any Atlantic front, the degree of cloud cover that suppresses long-wave heat loss, and boundary-layer wind speeds that limit surface decoupling. A slightly later or weaker frontal passage, or more extensive low cloud, would favor the warmer end of the range, while clearer skies and lighter winds would allow temperatures to fall closer to the official 14 °C forecast. Updated model runs and Met Office briefings over the next 24–48 hours will narrow these thresholds ahead of market resolution.